diff --git a/src/os/getwd.go b/src/os/getwd.go
index 64c3c4acd7e02e77c0421d641c1a6b7f3d5374bc..732ece7b098c0f1d9ad8649b9d2cf2c44518ebc3 100644
--- a/src/os/getwd.go
+++ b/src/os/getwd.go
@@ -15,10 +15,14 @@ var getwdCache struct {
 	dir string
 }
 
-// Getwd returns a rooted path name corresponding to the
+// Getwd returns an absolute path name corresponding to the
 // current directory. If the current directory can be
 // reached via multiple paths (due to symbolic links),
 // Getwd may return any one of them.
+//
+// On Unix platforms, if the environment variable PWD
+// provides an absolute name, and it is a name of the
+// current directory, it is returned.
 func Getwd() (dir string, err error) {
 	if runtime.GOOS == "windows" || runtime.GOOS == "plan9" {
 		dir, err = syscall.Getwd()